This commit is the result of running `yarn eslint --fix` after enabling
the `no-implicit-coercion` ESLint rule.  This rule has been added to
our ESLint config here:

https://gitlab.com/gitlab-org/gitlab-eslint-config/merge_requests/14

This is one of many MRs opened in order to improve the overall
internationalisation of the GitLab codebase.

This commit only targets Vanilla JS files.

i18n documentation
https://docs.gitlab.com/ee/development/i18n/externalization.html

In [!21565][0] we removed the loadCheck function from the LazyLoader for
images. The function seemed to be obsolete before anyhow, because we
make use of the MutationObserver in order to detect elements added /
removed from the DOM.

[0]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21565

See https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/3566

Only trigger loadCheck on open toggle, not close. Update specs and add right_sidebar_spec test for additions

Closes #38276

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/34261

See https://gitlab.com/gitlab-org/gitlab-ce/issues/34407

 - Revert https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/12399
 - Update https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/12299
   throttle/debounce to happen immediately and cleanup

Refactored slightly so that the same logic is shared between both the
expanded & the collapsed.